1. Field of the invention
This invention relates to a liquid level detector, particularly to a liquid level detector that performs non-contact and non-friction measurement with advantages in excellent durability, simple structure, high resolution, low cost, and easy fabrication.
2. Description of the prior art
As shown in FIG. 1, a prior liquid level detector mainly comprises a main body 10, a float ball 12, a connecting rod 14, a sensing head 16, a Ni--Cr coil 18, a pivot 20, and a signal wire 22. A circular casing is provided at lower end of the main body 10 for accommodating the Ni--Cr coil 18, which is formed by winding Ni--Cr wire on a Bakelite plate, and the pivot 20 is positioned at the center portion of the circular casing, wherein the connecting rod 14 is passing through the pivot 20 and attached thereto; and one end of the connecting rod 14 is extended and pivot-jointed with the float ball 12, while the other end of the connecting rod is coupled with the sensing head 16, which is propped by a spring to keep in touch with the arc shaped Ni--Cr coil 18. When the prior liquid level detector is applied to somewhere, say an oil tank, the float ball 12 is floating in the oil and the sensing head 16 is touching the Ni--Cr coil 18. Position of the floating ball 12 ascends or descends according to the liquid level to drive the sensing head 16 fixed at the connecting rod 14 to slide and contact on the Ni--Cr coil. Any change in impedance owing to displacement of the sensing head 16 will be transmitted via a signal wire 22 for being read on a display apparatus that will display data of liquid quantity. The defects of the abovesaid prior liquid level detector shall include: a complicated structure for applying the float ball 12, the connecting rod 14, the sensing head 16, the Ni--Cr coil 18, etc; high cost; shortened durability due to possible fracture of the Ni--Cr coil 18 that is whetted in the long term by touching of the sensing head 16; non-uniformity of the arc shaped Bakelite plate that may cause a clearance problem between the sensing head 16 and the Ni--Cr coil 18--the detector may fail to detect if clearance is too big, or, the coil may be fractured owing to friction if the clearance is too small; when the detector being applied under a quaking condition, such as in a mobile car, wherein the detector may be impaired or malfunctioned due to out of order of internal components.
In view of the above imperfections, the inventor is benefited with years of manufacturing experience in related field to have an improved construction of this invention developed and proposed.